Defrost fan rehab and rebuild thread (fresh air fan), or How the heck do if fix this thing? |
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Defrost fan rehab and rebuild thread (fresh air fan), or How the heck do if fix this thing? |
DRPHIL914 |
Jan 21 2021, 08:55 AM
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#54
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Dr. Phil Group: Members Posts: 5,808 Joined: 9-December 09 From: Bluffton, SC Member No.: 11,106 Region Association: South East States |
I have been dealing with this for 12 years, a non-running defrost fan. i even pulled this out 2 years ago and rebuilt it with new flapper seals and main body seal then made sure fan turned but didnt bench test the motor or resisitors, so as a result it still does not work properly. i will be documenting this because 914rubber and Mark will soon be putting together a kit for this that includes all the hardware seals and even a motor i believe, BUT i still have problems and questions!!! so i am starting this thread to get information on diagnosing the common causes of it not working and how to fix it, and then document the rebuild and replacement of the motor, fan, resistor and maybe the control unit in dash. Others have documented the reinstallation of the fan and the cables so i will not duplicate that. and we may want to link other threads hear that have done that as well.
Mark is sending me a kit soon, so while i wait for it, i will have to get some more information about the wiring and resistors function and how to test them . I had this out last week and tested 3 different control units due to thinking that my issue was a control issue, because it runs on one speed, #2, and anything else does not work and it will then throw the fuse. most assume this would be caused by bad slider unit but i tested 3 of them and 2 are like new with no wear on the sliders , still same result. so i am suspecting the resistors /plug aparatus . If anyone has done this and cares to share how to examine and test that for proper function, lets start there. Resistor function, which lead is which and examination of the control units I will take pictures of mine tonight and post those soon. once this figured out and fixed i will do a full step bystep on reassembly too. Looking for lots of help and input on this, thanks!!! Dr. Phil |
DRPHIL914 |
Feb 5 2021, 09:26 AM
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#55
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Dr. Phil Group: Members Posts: 5,808 Joined: 9-December 09 From: Bluffton, SC Member No.: 11,106 Region Association: South East States |
The fan cage used in URO Parts Blower Motor assembly 911 571 320 32 is indeed dynamically tested at the factory. Just pulled two random units off the shelf in the warehouse; one has a balancing clip and the other doesn't (probably didn't need it). Our impeller doesn't have degree marks, but it does have an arrow mark that's aligned with a small hole that's probably a reference point for an optical eye in the balancing device, and a screen tells the operator where to place the clip on the cage relative to the arrow. We sell a ton of these annually (also fits 911 up to 1989) and don't get any complaints. Would you be so kind as to weight a unit? I just received a 2nd blower/housing to replace my housing that was all busted up. I'll weigh this stock one. I would be be game to migrate to a new URO unit even if it only saves some weight of about 1/2 lb or so. No problem, the one in our photo weighs 556g / 1.226 lbs. How much does the OE weigh? I see a lot of them on ebay i assume the are all the same? look the same, some sellers like partscontainer carry them and price varies slightly but not much. We will document the build and testing of the unit here as well if thats ok? All of the URO brand units should be the same, don't believe we've made any running changes to these. These come in a plain brown box with a white and blue URO sticker, and a URO logo laser-marked as shown in the above photo. Documenting the build and testing would be fantastic, looking forward to it! well my new fan and motor assembly from URO arrived yesterday! so this will go in one of the fan housings that i have that will be rebuilt and sealed as soon as those parts arrive. I have one resistor pack that seems to be testing good , the other one i have to still figure out whats wrong with it before reassembly with the know stock oem fan and motor assembly, and the third one need a new motor so i ordered the brand new Bosch replacement motor to but into that fan, so 3 different ways to do this, depending on how deep you want to go, well even a 4th if you wanted to try and rebuild a motor but that does not appear to be possible on some of these according to how it looks from @Superhawy996 experiment turned out. he can confirm that, but the Fan/and motor assembly from URO is under $90. We just have to get the fan/housing seal, which 914rubber now makes, along with the flapper seals and seal for the lower fan to upper housing(diverter box). Now if we could source a new or OEM NOS stock of resistor packs i could do a nice rebuild service with new seals, motor, fan and resistor pack. |
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